Question

How to display information that there is no post instead 404 error?

How often does something like this in django?

def post_by_category(request, slug):
    category = get_object_or_404(Category, slug=slug)
    categories = category.get_descendants(include_self=True)
    posts = get_list_or_404(Post, category__in=categories)

    return render_to_response("by_category.html",
                              {'posts': posts, context_instance=RequestContext(request))

Answer 1

By using posts = get_list_or_404(Post, category__in=categories) you’re explicitly asking it to return a 404 in case there are no posts.

Try:

posts = Post.objects.filter(category__in=categories)
if posts:
    return render_to_response("by_category.html",
                              {'posts': posts}, context_instance=RequestContext(request))
else:
    return render_to_response("by_category.html",
                              {'message': 'No posts found!'}, context_instance=RequestContext(request))

And make sure you print out the error {{ message }} inside by_category.html.